The legion of fictional deities in the World of Greyhawk campaign setting for the Dungeons & Dragons fantasy roleplaying game covers an extensive range of spheres of influence, allowing players to customize the spiritual beliefs and powers of their characters, and as well as giving Dungeon Masters a long list of gods from which to design evil temples and minions. Although the Greyhawk campaign world, when it was merely a home game, started with no specific gods, the value of having deities available for both players and game plot purposes was quickly realized. The number of deities has varied with each version of the campaign world that has been published, but for many years numbered a few dozen. It has only been since 1999 that the number of gods increased dramatically to almost 200, due to the volume of newly published material that was subsequently integrated into the campaign world.
When Dungeons & Dragons was developed in the early 1970s by Gary Gygax and Dave Arneson, one of the archetypal character classes in the original game was the cleric, a character who received divine powers from “the gods”. However, when Gygax started to build his own campaign world called Greyhawk, one facet of culture that he did not address was organized religion. Since his campaign was largely built around the needs of lower-level characters, he didn't think specific deities were necessary, since direct interaction between a god and a low-level character was very unlikely. Some of his players took matters into their own hands, calling upon Norse or Greek gods such as Odin or Zeus, or even Conan's Crom in times of dire need. However, some of the players wanted Gygax to create and customize a specific deity so that cleric characters could receive their divine powers from someone less ambiguous than "the gods". Gygax, with tongue in cheek, created two gods: Saint Cuthbert—who brought non-believers around to his point of view with whacks of his cudgel —and Pholtus, whose fanatical followers refused to believe that any other gods existed. Because both of these deities represented aspects of Good, Gygax eventually created a few evil deities to provide some villainy.
In Gygax's serialized novella The Gnome Cache, which was set in Greyhawk, a shrine to St. Cuthbert (spelled "St. Cuthburt") is mentioned; this was the first published reference to a Greyhawk deity.